Signalling Mechanisms for Wireless Device Handover

ABSTRACT

A serving base station transmits, in response to making a handover decision for a wireless device, a first message to a target base station. The serving base station receives from the target base station a second message comprising configuration parameters of a plurality of cells. The configuration parameters comprise a cell group index for a secondary cell identifying a cell group. The serving base station transmits a third message to the wireless device. The third message comprises configuration parameters and is configured to cause the wireless device to start a synchronization process with the target base station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/662,191, filed Jun. 20, 2012, and U.S. Provisional Application No.61/679,103, filed Aug. 3, 2012, which are hereby incorporated byreference in its entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present inventionare described herein with reference to the drawings, in which:

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention;

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers in a carrier group as per an aspect of anembodiment of the present invention;

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention;

FIG. 4 is a block diagram of a base station and a wireless device as peran aspect of an embodiment of the present invention;

FIG. 5 is a diagram depicting uplink transmission timing of one or morecells in a first timing advance group (TAG) and a second TAG as per anaspect of an embodiment of the present invention;

FIG. 6 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention;

FIG. 7 shows example TAG configurations as per an aspect of anembodiment of the present invention;

FIG. 8 is an example flow diagram illustrating signaling messages duringa handover as per an aspect of an embodiment of the present invention;

FIG. 9 is an example flow diagram illustrating signaling messages duringa handover as per an aspect of an embodiment of the present invention;

FIG. 10 is an example flow diagram in a wireless device illustratingchanging configuration of cell groups as per an aspect of an embodimentof the present invention; and

FIG. 11 is an example flow diagram in a base station illustratingchanging configuration of cell groups as per an aspect of an embodimentof the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present invention enable operation ofmultiple timing advance groups. Embodiments of the technology disclosedherein may be employed in the technical field of multicarriercommunication systems. More particularly, the embodiments of thetechnology disclosed herein may relate to operation of multiple timingadvance groups.

Example embodiments of the invention may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may include, but are not limited to: CDMA (codedivision multiple access), OFDM (orthogonal frequency divisionmultiplexing), TDMA (time division multiple access), Wavelettechnologies, and/or the like. Hybrid transmission mechanisms such asTDMA/CDMA, and OFDM/CDMA may also be employed. Various modulationschemes may be applied for signal transmission in the physical layer.Examples of modulation schemes include, but are not limited to: phase,amplitude, code, a combination of these, and/or the like. An exampleradio transmission method may implement QAM (quadrature amplitudemodulation) using BPSK (binary phase shift keying), QPSK (quadraturephase shift keying), 16-QAM, 64-QAM, 256-QAM, and/or the like. Physicalradio transmission may be enhanced by dynamically or semi-dynamicallychanging the modulation and coding scheme depending on transmissionrequirements and radio conditions.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention. As illustrated in thisexample, arrow(s) in the diagram may depict a subcarrier in amulticarrier OFDM system. The OFDM system may use technology such asOFDM technology, SC-OFDM (single carrier-OFDM) technology, or the like.For example, arrow 101 shows a subcarrier transmitting informationsymbols. FIG. 1 is for illustration purposes, and a typical multicarrierOFDM system may include more subcarriers in a carrier. For example, thenumber of subcarriers in a carrier may be in the range of 10 to 10,000subcarriers. FIG. 1 shows two guard bands 106 and 107 in a transmissionband. As illustrated in FIG. 1, guard band 106 is between subcarriers103 and subcarriers 104. The example set of subcarriers A 102 includessubcarriers 103 and subcarriers 104. FIG. 1 also illustrates an exampleset of subcarriers B 105. As illustrated, there is no guard band betweenany two subcarriers in the example set of subcarriers B 105. Carriers ina multicarrier OFDM communication system may be contiguous carriers,non-contiguous carriers, or a combination of both contiguous andnon-contiguous carriers.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers as per an aspect of an embodiment of the presentinvention. A multicarrier OFDM communication system may include one ormore carriers, for example, ranging from 1 to 10 carriers. Carrier A 204and carrier B 205 may have the same or different timing structures.Although FIG. 2 shows two synchronized carriers, carrier A 204 andcarrier B 205 may or may not be synchronized with each other. Differentradio frame structures may be supported for FDD (frequency divisionduplex) and TDD (time division duplex) duplex mechanisms. FIG. 2 showsan example FDD frame timing. Downlink and uplink transmissions may beorganized into radio frames 201. In this example, radio frame durationis 10 msec. Other frame durations, for example, in the range of 1 to 100msec may also be supported. In this example, each 10 ms radio frame 201may be divided into ten equally sized sub-frames 202. Other subframedurations such as including 0.5 msec, 1 msec, 2 msec, and 5 msec mayalso be supported. Sub-frame(s) may consist of two or more slots 206.For the example of FDD, 10 subframes may be available for downlinktransmission and 10 subframes may be available for uplink transmissionsin each 10 ms interval. Uplink and downlink transmissions may beseparated in the frequency domain. Slot(s) may include a plurality ofOFDM symbols 203. The number of OFDM symbols 203 in a slot 206 maydepend on the cyclic prefix length and subcarrier spacing.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention. The resource grid structure intime 304 and frequency 305 is illustrated in FIG. 3. The quantity ofdownlink subcarriers or resource blocks (RB) (in this example 6 to 100RBs) may depend, at least in part, on the downlink transmissionbandwidth 306 configured in the cell. The smallest radio resource unitmay be called a resource element (e.g. 301). Resource elements may begrouped into resource blocks (e.g. 302). Resource blocks may be groupedinto larger radio resources called Resource Block Groups (RBG) (e.g.303). The transmitted signal in slot 206 may be described by one orseveral resource grids of a plurality of subcarriers and a plurality ofOFDM symbols. Resource blocks may be used to describe the mapping ofcertain physical channels to resource elements. Other pre-definedgroupings of physical resource elements may be implemented in the systemdepending on the radio technology. For example, 24 subcarriers may begrouped as a radio block for a duration of 5 msec. In an illustrativeexample, a resource block may correspond to one slot in the time domainand 180 kHz in the frequency domain (for 15 KHz subcarrier bandwidth and12 subcarriers).

FIG. 4 is an example block diagram of a base station 401 and a wirelessdevice 406, as per an aspect of an embodiment of the present invention.A communication network 400 may include at least one base station 401and at least one wireless device 406. The base station 401 may includeat least one communication interface 402, at least one processor 403,and at least one set of program code instructions 405 stored innon-transitory memory 404 and executable by the at least one processor403. The wireless device 406 may include at least one communicationinterface 407, at least one processor 408, and at least one set ofprogram code instructions 410 stored in non-transitory memory 409 andexecutable by the at least one processor 408. Communication interface402 in base station 401 may be configured to engage in communicationwith communication interface 407 in wireless device 406 via acommunication path that includes at least one wireless link 411.Wireless link 411 may be a bi-directional link. Communication interface407 in wireless device 406 may also be configured to engage in acommunication with communication interface 402 in base station 401. Basestation 401 and wireless device 406 may be configured to send andreceive data over wireless link 411 using multiple frequency carriers.According to some of the various aspects of embodiments, transceiver(s)may be employed. A transceiver is a device that includes both atransmitter and receiver. Transceivers may be employed in devices suchas wireless devices, base stations, relay nodes, and/or the like.Example embodiments for radio technology implemented in communicationinterface 402, 407 and wireless link 411 are illustrated are FIG. 1,FIG. 2, and FIG. 3. and associated text.

An interface may be a hardware interface, a firmware interface, asoftware interface, and/or a combination thereof. The hardware interfacemay include connectors, wires, electronic devices such as drivers,amplifiers, and/or the like. A software interface may include codestored in a memory device to implement protocol(s), protocol layers,communication drivers, device drivers, combinations thereof, and/or thelike. A firmware interface may include a combination of embeddedhardware and code stored in and/or in communication with a memory deviceto implement connections, electronic device operations, protocol(s),protocol layers, communication drivers, device drivers, hardwareoperations, combinations thereof, and/or the like.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayalso refer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics inthe device, whether the device is in an operational or non-operationalstate.

According to some of the various aspects of embodiments, an LTE networkmay include many base stations, providing a user plane (PDCP: packetdata convergence protocol/RLC: radio link control/MAC: media accesscontrol/PHY: physical) and control plane (RRC: radio resource control)protocol terminations towards the wireless device. The base station(s)may be interconnected with other base station(s) by means of an X2interface. The base stations may also be connected by means of an S1interface to an EPC (Evolved Packet Core). For example, the basestations may be interconnected to the MME (Mobility Management Entity)by means of the S1-MME interface and to the Serving Gateway (S-GW) bymeans of the S1-U interface. The S1 interface may support a many-to-manyrelation between MMEs/Serving Gateways and base stations. A base stationmay include many sectors for example: 1, 2, 3, 4, or 6 sectors. A basestation may include many cells, for example, ranging from 1 to 50 cellsor more. A cell may be categorized, for example, as a primary cell orsecondary cell. When carrier aggregation is configured, a wirelessdevice may have one RRC connection with the network. At RRC connectionestablishment/re-establishment/handover, one serving cell may providethe NAS (non-access stratum) mobility information (e.g. TAI-trackingarea identifier), and at RRC connection re-establishment/handover, oneserving cell may provide the security input. This cell may be referredto as the Primary Cell (PCell). In the downlink, the carriercorresponding to the PCell may be the Downlink Primary Component Carrier(DL PCC), while in the uplink, it may be the Uplink Primary ComponentCarrier (UL PCC). Depending on wireless device capabilities, SecondaryCells (SCells) may be configured to form together with the PCell a setof serving cells. In the downlink, the carrier corresponding to an SCellmay be a Downlink Secondary Component Carrier (DL SCC), while in theuplink, it may be an Uplink Secondary Component Carrier (UL SCC). AnSCell may or may not have an uplink carrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,is assigned a physical cell ID and a cell index. A carrier (downlink oruplink) belongs to only one cell, the cell ID or Cell index may alsoidentify the downlink carrier or uplink carrier of the cell (dependingon the context it is used). In the specification, cell ID may be equallyreferred to a carrier ID, and cell index may be referred to carrierindex. In implementation, the physical cell ID or cell index may beassigned to a cell. Cell ID may be determined using the synchronizationsignal transmitted on a downlink carrier. Cell index may be determinedusing RRC messages. For example, when the specification refers to afirst physical cell ID for a first downlink carrier, it may mean thefirst physical cell ID is for a cell comprising the first downlinkcarrier. The same concept may apply to, for example, carrier activation.When the specification indicates that a first carrier is activated, itequally means that the cell comprising the first carrier is activated.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in wireless device, base station, radio environment, network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, traffic load, initial systemset up, packet sizes, traffic characteristics, a combination of theabove, and/or the like. When the one or more criteria are met, theexample embodiments may be applied. Therefore, it may be possible toimplement example embodiments that selectively implement disclosedprotocols.

Example embodiments of the invention may enable operation of multipletiming advance groups. Other example embodiments may comprise anon-transitory tangible computer readable media comprising instructionsexecutable by one or more processors to cause operation of multipletiming advance groups. Yet other example embodiments may comprise anarticle of manufacture that comprises a non-transitory tangible computerreadable machine-accessible medium having instructions encoded thereonfor enabling programmable hardware to cause a device (e.g. wirelesscommunicator, UE, base station, etc.) to enable operation of multipletiming advance groups. The device may include processors, memory,interfaces, and/or the like. Other example embodiments may comprisecommunication networks comprising devices such as base stations,wireless devices (or user equipment: UE), servers, switches, antennas,and/or the like.

According to some of the various aspects of embodiments, serving cellshaving an uplink to which the same time alignment (TA) applies may begrouped in a TA group (TAG). Serving cells in one TAG may use the sametiming reference. For a given TAG, a user equipment (UE) may use onedownlink carrier as the timing reference at a given time. The UE may usea downlink carrier in a TAG as the timing reference for that TAG. For agiven TAG, a UE may synchronize uplink subframe and frame transmissiontiming of the uplink carriers belonging to the same TAG. According tosome of the various aspects of embodiments, serving cells having anuplink to which the same TA applies may correspond to the serving cellshosted by the same receiver. A TA group may comprise at least oneserving cell with a configured uplink. A UE supporting multiple TAs maysupport two or more TA groups. One TA group may contain the PCell andmay be called a primary TAG (pTAG). In a multiple TAG configuration, atleast one TA group may not contain the PCell and may be called asecondary TAG (sTAG). Carriers within the same TA group may use the sameTA value and the same timing reference.

FIG. 5 is a diagram depicting uplink transmission timing of one or morecells in a first timing advance group (TAG1) and a second TAG (TAG2) asper an aspect of an embodiment of the present invention. TAG1 mayinclude one or more cells, TAG2 may also include one or more cells. TAGtiming difference in FIG. 5 may be the difference in UE uplinktransmission timing for uplink carriers in TAG1 and TAG2. The timingdifference may range between, for example, sub micro-seconds to about 3omicro-seconds.

FIG. 7 shows example TAG configurations as per an aspect of anembodiment of the present invention. In Example 1, pTAG include PCell,and sTAG includes SCell1. In Example 2, pTAG includes PCell and SCell1,and sTAG includes SCell2 and SCell3. In Example 3, pTAG includes PCelland SCell1, and sTAG1 includes SCell2 and SCell3, and sTAG2 includesSCell4. Up to four TAGs may be supported and other example TAGconfigurations may also be provided. In many examples of thisdisclosure, example mechanisms are described for a pTAG and an sTAG. Theoperation with one example sTAG is described, and the same operation maybe applicable to other sTAGs. The example mechanisms may be applied toconfigurations with multiple sTAGs.

According to some of the various aspects of embodiments, TA maintenance,pathloss reference handling and the timing reference for pTAG may followLTE release 10 principles. The UE may need to measure downlink pathlossto calculate the uplink transmit power. The pathloss reference may beused for uplink power control and/or transmission of random accesspreamble(s). A UE may measure downlink pathloss using the signalsreceived on the pathloss reference cell. For SCell(s) in a pTAG, thechoice of pathloss reference for cells may be selected from and belimited to the following two options: a) the downlink SCell linked to anuplink SCell using the system information block 2 (SIB2), and b) thedownlink pCell. The pathloss reference for SCells in pTAG may beconfigurable using RRC message(s) as a part of SCell initialconfiguration and/or reconfiguration. According to some of the variousaspects of embodiments, PhysicalConfigDedicatedSCell information element(IE) of an SCell configuration may include the pathloss reference SCell(downlink carrier) for an SCell in pTAG. The downlink SCell linked to anuplink SCell using the system information block 2 (SIB2) may be referredto as the SIB2 linked downlink of the SCell. Different TAGs may operatein different bands. For an uplink carrier in an sTAG, the pathlossreference may be only configurable to the downlink SCell linked to anuplink SCell using the system information block 2 (SIB2) of the SCell.

To obtain initial uplink (UL) time alignment for an sTAG, eNB mayinitiate an RA procedure. In an sTAG, a UE may use one of any activatedSCells from this sTAG as a timing reference cell. In an exampleembodiment, the timing reference for SCells in an sTAG may be the SIB2linked downlink of the SCell on which the preamble for the latest RAprocedure was sent. There may be one timing reference and one timealignment timer (TAT) per TA group. TAT for TAGs may be configured withdifferent values. When the TAT associated with the pTAG expires: allTATs may be considered as expired, the UE may flush all HARQ buffers ofall serving cells, the UE may clear any configured downlinkassignment/uplink grants, and the RRC in the UE may release PUCCH/SRSfor all configured serving cells. When the pTAG TAT is not running, ansTAG TAT may not be running. When the TAT associated with sTAG expires:a) SRS transmissions may be stopped on the corresponding SCells, b) SRSRRC configuration may be released, c) CSI reporting configuration forthe corresponding SCells may be maintained, and/or d) the MAC in the UEmay flush the uplink HARQ buffers of the corresponding SCells.

Upon deactivation of the last SCell in an sTAG, the UE may not stop TATof the sTAG. In an implementation, upon removal of the last SCell in ansTAG, TAT of the TA group may not be running. RA procedures in parallelmay not be supported for a UE. If a new RA procedure is requested(either by UE or network) while another RA procedure is already ongoing,it may be up to the UE implementation whether to continue with theongoing procedure or start with the new procedure. The eNB may initiatethe RA procedure via a PDCCH order for an activated SCell. This PDCCHorder may be sent on the scheduling cell of this SCell. When crosscarrier scheduling is configured for a cell, the scheduling cell may bedifferent than the cell that is employed for preamble transmission, andthe PDCCH order may include the SCell index. At least a non-contentionbased RA procedure may be supported for SCell(s) assigned to sTAG(s).

FIG. 6 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention. eNB transmits an activation command 600 to activate an SCell.A preamble 602 (Msg1) may be sent by a UE in response to the PDCCH order601 on an SCell belonging to an sTAG. In an example embodiment, preambletransmission for SCells may be controlled by the network using PDCCHformat 1A. Msg2 message 603 (RAR: random access response) in response tothe preamble transmission on SCell may be addressed to RA-RNTI in PCellcommon search space (CSS). Uplink packets 604 may be transmitted on theSCell, in which the preamble was transmitted.

According to some of the various aspects of embodiments, initial timingalignment may be achieved through a random access procedure. This mayinvolve the UE transmitting a random access preamble and the eNBresponding with an initial TA command NTA (amount of timing advance)within the random access response window. The start of the random accesspreamble may be aligned with the start of the corresponding uplinksubframe at the UE assuming NTA=0. The eNB may estimate the uplinktiming from the random access preamble transmitted by the UE. The TAcommand may be derived by the eNB based on the estimation of thedifference between the desired UL timing and the actual UL timing. TheUE may determine the initial uplink transmission timing relative to thecorresponding downlink of the sTAG on which the preamble is transmitted.

A base station may communicate with a mix of wireless devices. Wirelessdevices may support multiple technologies, or multiple releases of thesame technology, have some specific capability depending on the wirelessdevice category and/or capability. A base station may comprise multiplesectors. When this disclosure refers to a base station communicatingwith a plurality of wireless devices, this disclosure may refer to asubset of the total wireless devices in the coverage area. Thisdisclosure may refer to, for example, a plurality of wireless devices ofa given LTE release with a given capability and in a given sector of thebase station. The plurality of wireless devices in this disclosure mayrefer to a selected plurality of wireless devices, and/or a subset oftotal wireless devices in the coverage area, which perform according tothe disclosed methods, and/or the like. There may be many wirelessdevices in the coverage area that may not comply with the disclosedmethods, for example, because those wireless devices perform based onolder releases of LTE technology. A time alignment command MAC controlelement may be a unicast MAC command transmitted to a wireless device.

According to some of the various aspects of various embodiments, thebase station or wireless device may group cells into a plurality of cellgroups. The term “cell group” may refer to a timing advance group (TAG)or a timing alignment group or a time alignment group. Time alignmentcommand may also be referred to timing advance command. A cell group mayinclude at least one cell. A MAC TA command may correspond to a TAG. Acell group may explicitly or implicitly be identified by a TAG index.Cells in the same band may belong to the same cell group. A first cell'sframe timing may be tied to a second cell's frame timing in a TAG. Whena time alignment command is received for the TAG, the frame timing ofboth first cell and second cell may be adjusted. Base station(s) mayprovide TAG configuration information to the wireless device(s) by RRCconfiguration message(s).

The mapping of a serving cell to a TAG may be configured by the servingeNB with RRC signaling. The mechanism for TAG configuration andreconfiguration may be based on RRC signaling. According to some of thevarious aspects of embodiments, when an eNB performs SCell additionconfiguration, the related TAG configuration may be configured for theSCell. In an example embodiment, eNB may modify the TAG configuration ofan SCell by removing (releasing) the SCell and adding(configuring) a newSCell (with the same physical cell ID and frequency) with an updated TAGID. The new SCell with the updated TAG ID may be initially inactivesubsequent to being assigned the updated TAG ID. eNB may activate theupdated new SCell and then start scheduling packets on the activatedSCell. In an example implementation, it may not be possible to changethe TAG associated with an SCell, but rather, the SCell may need to beremoved and a new SCell may need to be added with another TAG. Forexample if there is a need to move an SCell from an sTAG to a pTAG, atleast one RRC message, for example, at least one RRC reconfigurationmessage, may be send to the UE to reconfigure TAG configurations byreleasing the SCell and then configuring the SCell as a part of pTAG(when an SCell is added/configured without a TAG index, the SCell isexplicitly assigned to pTAG). The PCell may not change its TA group andmay always be a member of the pTAG.

An eNB may perform initial configuration based on initial configurationparameters received from a network node (for example a managementplatform), an initial eNB configuration, a UE location, a UE type, UECSI feedback, UE uplink transmissions (for example, data, SRS, and/orthe like), a combination of the above, and/or the like. For example,initial configuration may be based on UE channel state measurements orreceived signal timing. For example, depending on the signal strengthreceived from a UE on various SCells downlink carrier or bydetermination of UE being in a repeater coverage area, or a combinationof both, an eNB may determine the initial configuration of sTAGs andmembership of SCells to sTAGs.

In an example implementation, the TA value of a serving cell may change,for example due to UE's mobility from a macro-cell to a repeater or anRRH (remote radio head) coverage area. The signal delay for that SCellmay become different from the original value and different from otherserving cells in the same TAG. In this scenario, eNB may re-configurethis TA-changed serving cell to another existing TAG. Or alternatively,the eNB may create a new TAG for the SCell based on the updated TAvalue. The TA value may be derived, for example, through eNBmeasurement(s) of signal reception timing, a RA mechanism, or otherstandard or proprietary processes. An eNB may realize that the TA valueof a serving cell is no longer consistent with its current TAG. Theremay be many other scenarios which require eNB to reconfigure TAGs.During reconfiguration, the eNB may need to move the reference SCellbelonging to an sTAG to another TAG. In this scenario, the sTAG wouldrequire a new reference SCell. In an example embodiment, the UE mayselect an active SCell in the sTAG as the reference timing SCell.

eNB may consider UE's capability in configuring multiple TAGs for a UE.UE may be configured with a configuration that is compatible with UEcapability. Multiple TAG capability may be an optional feature and perband combination Multiple TAG capability may be introduced. UE maytransmit its multiple TAG capability to eNB via an RRC message and eNBmay consider UE capability in configuring TAG configuration(s).

The purpose of an RRC connection reconfiguration procedure may be tomodify an RRC connection, (e.g. to establish, modify and/or release RBs,to perform handover, to setup, modify, and/or release measurements, toadd, modify, and/or release SCells). If the received RRC ConnectionReconfiguration message includes the sCellToReleaseList, the UE mayperform an SCell release. If the received RRC Connection Reconfigurationmessage includes the sCellToAddModList, the UE may perform SCelladditions or modification.

The parameters related to SCell random access channel may be common toall UEs. For example PRACH configuration (RACH resources, configurationparameters, RAR window) for the SCell may be common to UEs. RACHresource parameters may include prach-configuration index, and/orprach-frequency offset. SCell RACH common configuration parameters mayalso include power: power ramping parameter(s) for preambletransmission; and max number of preamble transmission parameter. It ismore efficient to use common parameters for RACH configuration, sincedifferent UEs will share the same random access channel.

eNB may transmit at least one RRC message to configure PCell, SCell(s)and RACH, and TAG configuration parameters. MAC-MainConfig may include atimeAlignmentTimerDedicated IE to indicate time alignment timer valuefor the pTAG. MAC-MainConfig may further include an IE including asequence of at least one (sTAG ID, and TAT value) to configure timealignment timer values for sTAGs. In an example, a first RRC message mayconfigure TAT value for pTAG, a second RRC message may configure TATvalue for sTAG1, and a third RRC message may configure TAT value forsTAG2. There is no need to include all the TAT configurations in asingle RRC message. In an example embodiment they may be included in oneor two RRC messages. The IE including a sequence of at least one (sTAGID, and TAT) value may also be used to update the TAT value of anexisting sTAG to an updated TAT value. The at least one RRC message mayalso include sCellToAddModList including at least one SCellconfiguration parameters. The radioResourceConfigDedicatedSCell(dedicated radio configuration IEs) in sCellToAddModList may include anSCell MAC configuration comprising TAG ID for the corresponding SCelladded or modified. The radioResourceConfigDedicatedSCell may alsoinclude pathloss reference configuration for an SCell. If TAG ID is notincluded in SCell configuration, the SCell is assigned to the pTAG. Inother word, a TAG ID may not be included inradioResourceConfigDedicatedSCell for SCells assigned to pTAG. TheradioResourceConfigCommonSCell (common radio configuration IEs) insCellToAddModList may include RACH resource configuration parameters,preamble transmission power control parameters, and other preambletransmission parameter(s). At the least one RRC message configuresPCell, SCell, RACH resources, and/or SRS transmissions and may assigneach SCell to a TAG (implicitly for pTAG or explicitly for sTAG). PCellis always assigned to the pTAG.

According to some of the various aspects of embodiments, a base stationmay transmit at least one control message to a wireless device in aplurality of wireless devices. The at least one control message is forexample, RRC connection reconfiguration message, RRC connectionestablishment message, RRC connection re-establishment message, and/orother control messages configuring or reconfiguring radio interface,and/or the like. The at least one control message may be configured tocause, in the wireless device, configuration of at least: I) a pluralityof cells. Each cell may comprise a downlink carrier and zero or oneuplink carrier. The configuration may assign a cell group index to acell in the plurality of cells. The cell group index may identify one ofa plurality of cell groups. A cell group in the plurality of cell groupsmay comprise a subset of the plurality of cells. The subset may comprisea reference cell with a reference downlink carrier and a referenceuplink carrier. Uplink transmissions by the wireless device in the cellgroup may employ the reference cell (the primary cell in pTAG and asecondary cell in an sTAG). The wireless device may employ asynchronization signal transmitted on the reference downlink carrier astiming reference to determine a timing of the uplink transmissions. Thesynchronization signal for example may be a) primary/secondarysynchronization signal, b) reference signal(s), and/or c) a combinationof a) and b). II) a time alignment timer for each cell group in theplurality of cell groups; and/or III) an activation timer for eachconfigured secondary cell.

The base station may transmit a plurality of timing advance commands.Each timing advance command may comprise: a time adjustment value, and acell group index. A time alignment timer may start or may restart whenthe wireless device receives a timing advance command to adjust uplinktransmission timing on a cell group identified by the cell group index.A cell group may be considered out-of-sync, by the wireless device, whenthe associated time alignment timer expires or is not running. The cellgroup may be considered in-sync when the associated time alignment timeris running.

The timing advance command may causes substantial alignment of receptiontiming of uplink signals in frames and subframes of all activated uplinkcarriers in the cell group at the base station. The time alignment timervalue may be configured as one of a finite set of predetermined values.For example, the finite set of predetermined values may be eight. Eachtime alignment timer value may be encoded employing three bits. TAG TATmay be a dedicated time alignment timer value and is transmitted by thebase station to the wireless device. TAG TAT may be configured to causeconfiguration of time alignment timer value for each time alignmentgroup. The IE TAG TAT may be used to control how long the UE isconsidered uplink time aligned. It corresponds to the timer for timealignment for each cell group. Its value may be in number of sub-frames.For example, value sf500 corresponds to 500 sub-frames, sf750corresponds to 750 sub-frames and so on. An uplink time alignment iscommon for all serving cells belonging to the same cell group. In anexample embodiment, the IE TAG TAT may be defined as: TAGTAT::=SEQUENCE{TAG ID, ENUMERATED {sf500, sf750, sf1280, sf1920, sf2560,sf5120, sf10240, infinity}}. Time alignment timer for pTAG may beindicated in a separate IE and may not be included in the sequence.

In an example, TimeAlignmentTimerDedicated IE may be sf500, and then TAGTAT may be {1, sf500; 2, sf2560; 3, sf500}. In the example, timealignment timer for the pTAG is configured separately and is notincluded in the sequence. In the examples, TAG0 (pTAG) time alignmenttimer value is 500 subframes (500 m-sec), TAG1 (sTAG) time alignmenttimer value is 500 subframes, TAG2 time alignment timer value is 2560subframes, and TAG3 time alignment timer value is 500 subframes. This isfor example purposes only. In this example a TAG may take one of 8predefined values. In a different embodiment, the enumerated valuescould take other values.

FIG. 8 is an example flow diagram illustrating signalling messagesduring a handover as per an aspect of an embodiment of the presentinvention. An important issue with respect to TAG configuration is howTAG configuration may be maintained or updated during a handover. A UEmay be configured with a first TAG configuration with a serving eNB. Atarget eNB may maintain the same TAG configuration, or may update the UETAG configuration. The target eNB may have a different cellconfiguration and may require a different TAG configuration. In anotherexample embodiment, the target eNB may employ cells with the samefrequencies as the serving cell and may require maintaining the same TAGconfiguration. The target eNB may configure TAG configuration after thehandover is completed or may configure TAG configuration during thehandover process. Release 10 of LTE does not support multiple TAGconfiguration, and addressing the TAG configuration changes duringhandover is not addressed in release 10 LTE technology. There is a needfor developing a signalling flow, UE processes, and eNB processes toaddress TAG configuration and TAG configuration parameter handlingduring the handover to reduce the handover overhead and delay, andincrease handover efficiency. Furthermore, there is a need to develophandover signalling and handover message parameters to address TAGconfiguration during a handover process.

According to some of the various aspects of embodiments, inRRC_CONNECTED mode, the network may control UE mobility, for example,the network may decide when the UE connects to which E-UTRA cell(s) orinter-RAT cell. For network controlled mobility in RRC_CONNECTED, thePCell may be changed using an RRC Connection Reconfiguration messageincluding the mobilityControlInfo (handover). The SCell(s) may bechanged using the RRC Connection Reconfiguration message either with orwithout the mobilityControlInfo. The network may trigger the handoverprocedure e.g. based on radio conditions, load, QoS, UE category, and/orthe like. To facilitate this, the network may configure the UE toperform measurement reporting (possibly including the configuration ofmeasurement gaps). The network may also initiate handover blindly, forexample without having received measurement reports from the UE. Beforesending the handover message to the UE, the source eNB may prepare oneor more target cells. The source eNB may select the target PCell. Thesource eNB may also provide the target eNB with a list of best cells oneach frequency for which measurement information is available, forexample, in order of decreasing RSRP. The source eNB may also includeavailable measurement information for the cells provided in the list.The target eNB may decide which SCells are configured for use afterhandover, which may include cells other than the ones indicated by thesource eNB.

According to some of the various aspects of embodiments, the target eNBmay generate a message used to configure the UE for the handover, forexample, the message including the access stratum configuration to beused in the target cell(s). The source eNB may transparently (forexample, does not alter values/content) forward the handovermessage/information received from the target eNB to the UE. Whenappropriate, the source eNB may initiate data forwarding for (a subsetof) the dedicated radio bearers. After receiving the handover message,the UE may attempt to access the target PCell at the available RACHoccasion according to a random access resource selection. Whenallocating a dedicated preamble for the random access in the targetPCell, E-UTRA may ensure the preamble is available from the first RACHoccasion the UE may use. Upon successful completion of the handover, theUE may send a message used to confirm the handover to the target eNB.

According to some of the various aspects of embodiments, if the targeteNB does not support the release of RRC protocol which the source eNBused to configure the UE, the target eNB may be unable to comprehend theUE configuration provided by the source eNB. In this case, the targeteNB may use the full configuration option to reconfigure the UE forhandover and re-establishment. Full configuration option includes aninitialization of the radio configuration, which makes the procedureindependent of the configuration used in the source cell(s) with theexception that the security algorithms are continued for the RRCre-establishment.

According to some of the various aspects of embodiments, after thesuccessful completion of handover, PDCP SDUs may be re-transmitted inthe target cell(s). This may apply for dedicated radio bearers usingRLC-AM mode and/or for handovers not involving full configurationoption. After the successful completion of handover not involving fullconfiguration option, the SN (sequence number) and/or the HFN (hyperframe number) may be reset for some radio bearers. For the dedicatedradio bearers using RLC-AM mode both SN and HFN may continue. Forreconfigurations involving the full configuration option, the PDCPentities may be newly established (SN and HFN may not continue) fordedicated radio bearers irrespective of the RLC mode. UE behaviour to beperformed upon handover may be the same regardless of the handoverprocedures used within the network (e.g. whether the handover includesX2 or S1 signalling procedures).

The source eNB may, for some time, maintain a context to enable the UEto return in case of handover failure. After having detected handoverfailure, the UE may attempt to resume the RRC connection either in thesource PCell or in another cell using the RRC re-establishmentprocedure. This connection resumption may succeed if the accessed cellis prepared. For example, when the access cell is a cell of the sourceeNB or of another eNB towards which handover preparation has beenperformed. The cell in which the re-establishment procedure succeedsbecomes the PCell while SCells, if configured, may be released.

Normal measurement and mobility procedures may be used to supporthandover to cells broadcasting a CSG (closed subscriber group) identity.In addition, E-UTRAN may configure the UE to report that it is enteringor leaving the proximity of cell(s) included in its CSG whitelist.E-UTRAN may request the UE to provide additional information broadcastby the handover candidate cell e.g. cell global identity, CSG identity,CSG membership status. E-UTRAN may use the proximity report to configuremeasurements as well as to decide whether or not to request additionalinformation broadcast by the handover candidate cell. The additionalinformation may be used to verify whether or not the UE is authorised toaccess the target PCell and may also be needed to identify handovercandidate cell. This may involve resolving PCI confusion, for example,when the physical layer identity that is included in the measurementreport may not uniquely identify the cell.

According to some of the various aspects of embodiments, the mapping ofa serving cell to a TA group may be configured by the serving eNB withRRC signalling. The mechanism for TAG configuration and reconfigurationmay be based on RRC signalling. When needed, the mapping between anSCell and a TA group may be reconfigured with RRC signalling. Themapping between an SCell and a TAG may not be reconfigured with RRCwhile the SCell is configured. For example if there is a need to move anSCell from an sTAG to a pTAG, at least one RRC message, for example atleast one RRC reconfiguration message, may be send to the UE toreconfigure TAG configurations. PCell may not change TA group and mayalways be a member of the pTAG.

According to some of the various aspects of embodiments, when an eNBperforms SCell addition configuration, the related TAG configuration maybe configured for the SCell. eNB may modify TAG configuration of anSCell by removing (releasing) the SCell and adding a new SCell (withsame physical cell ID and frequency) with an updated TAG ID. The newSCell with the updated TAG ID may be initially inactive subsequent tojoining the updated TAG ID. eNB may activate the updated new SCell andthen start scheduling packets on the activated SCell. It may not bepossible to change the TAG associated with an SCell but rather the SCellneeds to be removed and a new SCell needs to be added with another TAG.This may not employ mobilityControlInfo in the RRC reconfigurationmessage.

According to some of the various aspects of embodiments, an eNB mayconsider UE's capability in configuring multiple TAGs for a UE. UE maybe configured with a configuration that is compatible with UEcapability. Multiple TAG capability is an optional feature in LTErelease 11 and multiple TAG capability may be introduced per bandcombination. UE may transmit its multiple TAG capability to eNB via anRRC message and eNB may consider UE capability in configuring TAGconfiguration.

The purpose of RRC connection reconfiguration procedure may be to modifyan RRC connection, e.g. to establish, modify and/or release RBs, toperform handover, to setup, modify, and/or release measurements, to add,modify, and/or release SCells. As part of the procedure, NAS dedicatedinformation may be transferred from E-UTRAN to the UE. If the receivedRRC Connection Reconfiguration message includes the sCellToReleaseList,UE performs SCell release. If the received RRC ConnectionReconfiguration message includes the sCellToAddModList, UE performsSCell additions or modification.

The UE context within the source eNB may contain information regardingroaming/handover restrictions which may be provided either at connectionestablishment or at the last TA (tracking area) update process. Thesource eNB may configure the UE measurement procedures employing atleast one RRC connection reconfiguration message. The UE may betriggered to send at least one measurement report by the rules set by,for example, system information, RRC configuration, and/or the like. Thesource eNB may make a handover decision based on many parameters, forexample, the measurement reports, RRM information, traffic and load, acombination of the above, and/or the like. The source eNB may initiatethe handover procedure by sending a handover request message to one ormore potential target eNBs. When the source eNB sends the handoverrequest message, it may start a handover preparation timer. Uponreception of the handover request acknowledgement message the source eNBmay stop the handover preparation timer.

The source eNB may transmit a handover request message to one or morepotential target eNB passing information to prepare the handover at thetarget side. The handover request message may comprise time alignmentcapability information of the UE. The target eNB may employ the timealignment capability of the UE in order to properly configure TAGconfiguration of the UE before UE connects to the target UE. The targeteNB may configure the UE considering the TAG configuration limitationsand capabilities of the UE. For example, if the UE does not supportmultiple TAG capability, the target eNB may not configure the UE withmultiple TAGs. In another example, if the UE does not support multipleTAG configuration with a certain band combinations, the eNB may considerthis limitation in TAG configurations. In another example, a UE may notsupport inter-band TAG configuration, and eNB may consider this inconfiguring the UE before the UE accesses the target eNB. In anotherexample embodiment, handover request message may further comprise thecurrent multiple TAG configuration of the UE connected to the servingeNB.

During the handover preparation phase, the serving eNB may transmit UE'smultiple TAG capability and/or UE's current multiple TAG configuration(TAG configuration of the UE in connection with the serving eNB) to oneor more potential target eNBs. This information may be employed, atleast in part, by the potential target eNB to configure the UE, forexample, to configure multiple TAG configuration parameters.

Handover admission control may be performed by the target eNB dependenton many factors, for example, QoS required for the UE bearers, UEcapabilities, UE configuration, target eNB load, a combination of theabove, and/or the like. The target eNB may configure the requiredresources according to the received information from the serving eNB andmay reserve a C-RNTI and/or a RACH preamble. The access stratumconfiguration to be used in the target cell may be specifiedindependently (for example as an establishment) or as a delta comparedto the access stratum-configuration used in the source cell (for exampleas a reconfiguration).

The target eNB may prepare handover with L1/L2 and may send the handoverrequest acknowledge message to the source eNB. The handover requestacknowledge message may include a transparent container to be sent tothe UE as an RRC message to perform the handover. The container mayinclude a new C-RNTI, target eNB security algorithm identifiers for theselected security algorithms, a dedicated RACH preamble, accessparameters, SIBs, and/or other configuration parameters. The transparentcontainer may further comprise the multiple TAG configurations forconnection of the UE to the target eNB. The multiple TAG configurationsmay modify the TAG configuration of the UE or may keep the same TAGconfiguration that the UE has with the serving base station. The targeteNB may generate the RRC message to perform the handover, for example,RRC connection reconfiguration message including the mobility controlinformation. The RRC message may be sent by the source eNB towards theUE. The source eNB may perform the necessary integrity protection andciphering of the message. The UE may receive the RRC connectionreconfiguration message from the source eNB and may start performing thehandover. The UE may not need to delay the handover execution fordelivering the HARQ/ARQ responses to the source eNB.

After receiving the RRC connection reconfiguration message including themobility control information, UE may perform synchronisation to thetarget eNB and accesses the target cell via RACH on the primary cell. UERandom access procedure may employ a contention-free procedure if adedicated RACH preamble was indicated in the mobility controlinformation. The UE random access procedure may employ acontention-based procedure if no dedicated preamble was indicated. UEmay derive target eNB specific keys and may configure the selectedsecurity algorithms to be used in the target cell. The target eNB mayrespond with uplink allocation and timing advance. After the UE hassuccessfully accessed the target cell, the UE may send an RRC connectionreconfiguration complete message (C-RNTI) to confirm the handover and toindicate that the handover procedure is completed for the UE. UE maytransmit a MAC uplink Buffer Status Report (BSR) Control Element (CE)along with the uplink RRC Connection Reconfiguration Complete message ormay transmit a MAC uplink BSR CE whenever possible to the target eNB.The target eNB verifies the C-RNTI sent in the RRC ConnectionReconfiguration Complete message. The target eNB may now begin sendingdata to the UE and receiving data from the UE.

FIG. 8 is an example flow diagram illustrating signalling messagesduring a handover as per an aspect of an embodiment of the presentinvention. According to some of the various aspects of embodiments, aserving base station may receive a first message from a wireless deviceon a primary cell in a plurality of cells at block 800. The firstmessage may be an RRC UE capability message. The plurality of cells maycomprise the primary cell and at least one secondary cell. The firstmessage may comprise at least one parameter indicating whether thewireless device supports configuration of a plurality of time alignmentgroups (TAGs). The base station may receive a plurality of radiocapability parameters from the wireless device.

In an example embodiment, the capability may be received on a firstsignalling bearer on the primary cell. The plurality of radio capabilityparameters may comprise a first sequence of one or more radioconfiguration parameters. A first radio configuration parameter in thefirst sequence may comprise a first parameter indicating whethermultiple timing advance groups may be supported for a first bandcombination. The first band combination may be in a second sequence ofone or more band combinations. The index of the first radioconfiguration parameter in the first sequence may determine the index ofthe first band combination in the second sequence.

According to some of the various embodiments, the size of the firstsequence may be the same as the size of the second sequence. The indexmay determine the order of: the first radio configuration parameter inthe first sequence; and the first band combination in the secondsequence. The first band combination may be identified by a first bandcombination parameter. The first band combination parameter may comprisea list of band identifier(s). Each of the band identifier(s) may be oneof a finite set of numbers. Each of the numbers may identify a specificband.

According to some of the various embodiments, the wireless device maysupport multiple inter-band timing advance groups if the list of bandidentifier(s) includes more than one band; and the first parameterindicates that multiple timing advance groups are supported. In yetother embodiments, the wireless device may support multiple intra-bandtiming advance groups if the list of band identifier(s) includes oneband; and the first parameter indicates that multiple timing advancegroups are supported.

According to some of the various embodiments, the wireless device maynot support multiple timing advance configurations if none of the radioconfiguration parameters comprise a parameter indicating that multipletiming advance groups are supported.

An example is provided to further explain an embodiment. A wirelessdevice may transmit an RRC message comprising UE capability information.The UE capability information may comprise an information elementcomprising a wireless device LTE radio capability parameters. The LTEradio capability parameters may comprise a plurality of parametersindicating various capability of the wireless device LTE radio. Theplurality of radio capability parameters may comprise a second sequenceof one or more band combinations. Each band combination IE parameter inthe second sequence of one or more band combinations may comprise a listof one or more band identifier(s). An example band combination IE may be{(band-id1, band-parameters1), (band-id2, band-parameters2), (band-id3,band-parameters3). The example band combination IE comprises a sequenceof band identifier(s): band-id1, band-id2, band-id3, and a sequence ofband parameters. Band parameters may be uplink parameter(s) and/ordownlink parameter(s). Each of the band identifier(s) may be one of afinite set of numbers, for example from a set of (1 . . . 64). Each ofthe numbers in the set may identify a specific band, for example number14 may refer to 1950 MHz band-A, 23 may refer to 2100 MHz band-D, 24 mayrefer to 2100 MHz band-E. If band-id1=14, the band-id2=23, andband-id3=24, the wireless device supports band combination of thesethree bands. A second band combination in the second sequence mayinclude band-id1=14 and band-id4=43. In the example, the second sequenceof one or more band combinations are considered an array of one or moreband combination IEs. In the example embodiment, two band combinationsare in the second sequence of one or more band combinations.

In the example embodiment, a first sequence of one or more radioconfiguration parameters for example could be {(TAG-not-supported, otherparameters1), (TAG-supported, other parameters2)}. The first radioconfiguration parameter is TAG-non-supported (with index 1), and thesecond radio configuration parameter is TAG-supported (with index 2).Index 1 in the first sequence comprise (TAG-non-supported) andcorresponds to first index in the second sequence (the first bandcombination: band-id1=14, the band-id2=23, and band-id3=24). Index 2 inthe first sequence comprise (TAG-supported) corresponds to index 2 inthe second sequence (the second band combination band-id1 and band-id4).In the example, TAG configuration is not supported for bandcombination=(band-id1=14, the band-id4=43, and band-id3=24). TAGconfiguration is supported for band combination=(band-id1=14, theband-id2=43).

The serving base station may selectively transmit at least one secondmessage to the wireless device if the at least one parameter indicatessupport for configuration of the plurality of TAGs at block 802. The atleast one second message may configure a first plurality of TAGs in thewireless device. If the e at least one parameter does not indicatesupport for configuration of the plurality of TAGs, the base station maynot configure a plurality of TAGs in the wireless device. If the atleast one parameter indicates support for configuration of the pluralityof TAGs, the base station may or may not configure the first pluralityof TAGs in the wireless device depending on the required wireless deviceconfiguration and many other parameters. Transmission or nottransmission (selective transmission) of at least one second message toconfigure the first plurality of TAGs is determined by the base stationbased on many criteria described in this specification.

The at least one second control message may be configured to cause inthe wireless device: i) configuration of at least one secondary cell inthe plurality of cells; and ii) assignment of each of the at least onesecondary cell to a TAG in a first plurality of TAGs. The firstplurality of TAGs may comprise a primary TAG and a secondary TAG. Theprimary TAG may comprise a first subset of the plurality of cells. Thefirst subset may comprise the primary cell. Uplink transmissions by thewireless device in the primary TAG may employ a first synchronizationsignal transmitted on the primary cell as a primary timing reference.The secondary TAG may comprise a second subset of the at least onesecondary cell. Uplink transmissions in the secondary TAG may employ asecond synchronization signal on an activated secondary cell in thesecondary TAG as a secondary timing reference.

The at least one second control message may be configured to furthercause in the wireless device configuration of a time alignment timer foreach of the first plurality of TAGs. The time alignment timer may startor restart in response to the wireless device receiving a timing advancecommand to adjust uplink transmission timing of a commanded TAG in thefirst plurality of TAGs. The at least one second control message maycomprise a media access control dedicated information element comprisinga sequence of at least one first information element. Each of the atleast one first information element may comprise: a first TAG index of afirst secondary TAG and a first time alignment timer value for the firstsecondary TAG. The at least one second control message may comprise atleast one cell add-modify information element. Each of the at least onecell add-modify information element may comprise a first plurality ofdedicated parameters. The first plurality of dedicated parameters maycomprise a first cell index for a first secondary cell in the at leastone secondary cell. The at least one second control message may furtherinclude configuration information for physical channels for the wirelessdevice. The at least one second control message may be configured tofurther cause the wireless device to set up or modify at least one radiobearer.

The serving base station may receive at least one measurement reportfrom the wireless device in response to the at least one second message.The at least one measurement report may comprise signal qualityinformation of at least one of the at least one cell of at least one ofthe at least one target base station. The signal quality information maybe derived at least in part employing measurements of at least one OFDMsubcarrier. The serving base station may make a handover decision,based, at least in part, on the at least one measurement report, and/orother parameters, such as load, QoS, mobility, etc. The serving basestation may also make a blind decision depending on base stationinternal proprietary algorithm.

The serving base station may transmit at least one third message to atleast one of the at least one target base station at block 804. The atleast one third message may comprise the at least one parameterindicating whether the wireless device supports configuration of aplurality of time alignment groups. The at least one third message maycomprise a plurality of parameters of the configuration at leastindicating association between at least one cell and a correspondingcell group index (configuration information of said first pluralityTAGs). The at least one third message may be a handover request messagetransmitted to at least one target base station to prepare the targetbase stations for the handover of the wireless device. The UE capabilityparameters may be included in the at least one third message.Furthermore, UE dedicated radio parameters comprising UE multiple TAGconfiguration may also be included in the handover request message. UEdedicated radio parameters may comprise MACMainconfig informationelement. UE dedicated radio parameters may comprise TAG configurationincluding TAG indices and associated cell indices, and time alignmenttimer value for each cell group.

FIG. 9 is an example flow diagram illustrating signalling messagesduring a handover as per an aspect of an embodiment of the presentinvention. According to some of the various aspects of embodiments, aserving base station, in response to making a handover decision by theserving base station for a wireless device, may transmit at least onethird message to at least one target base station at block 900. Thethird message(s) in block 900 of FIG. 9 is the same as the thirdmessage(s) in block 804 of FIG. 8. The at least one third message maycomprise the at least one parameter indicating whether the wirelessdevice supports configuration of a plurality of time alignment groups.The format of the parameter (information element) indicating whether thewireless device supports configuration of a plurality of time alignmentgroups is the same format as the UE capability message transmitted bythe wireless device to the base station in the first message asdescribed in the specification. The at least one third message mayfurther comprise a plurality of parameters of the configuration at leastindicating association between at least one cell and a correspondingcell group index (configuration information of said first pluralityTAGs). The parameters included in the configuration information of saidfirst plurality TAGs may be the same as the ones included in the atleast one second message as described in this specification. The atleast one third message may be a handover request message transmitted toat least one target base station to prepare the target base stations forthe handover of the wireless device. The UE capability parameters may beincluded in the at least one third message. Furthermore, UE dedicatedradio parameters comprising UE multiple TAG configuration may also beincluded in the handover request message. UE dedicated radio parametersmay comprise MACMainconfig information element. UE dedicated radioparameters may comprise TAG configuration including TAG indices andassociated cell indices, and time alignment timer value for each cellgroup.

The serving base station may receive from one of the at least one targetbase station at least one fourth message at block 902. The at least onefourth message may comprise configuration of a plurality of cells forthe wireless device. The plurality of cells may comprise a primary celland at least one secondary cell. The configuration may associate a cellin the plurality of cells with a cell group index. The cell group indexmay identify one of a plurality of cell groups. The plurality of cellgroups may comprise a primary cell group and a secondary cell group. Aprimary cell group may comprise a first subset of the plurality ofcells. The first subset may comprise the primary cell. A secondary cellgroup may comprise a second subset of the at least one secondary cell.

The serving base station may transmit a fifth message to the wirelessdevice at block 904. The fifth message may comprise a plurality ofparameters of the configuration at least indicating association betweenat least one cell and a corresponding cell group index (configurationinformation of a plurality TAGs). The fifth message may cause thewireless device to start a synchronization process with the target basestation (with a cell in the target base station).

The fifth message may be configured to further cause in the wirelessdevice configuration of a time alignment timer for each of the pluralityof cell groups. The fifth message may comprise a media access controldedicated information element comprising a sequence of at least onefirst information element. Each of the at least one first informationelement may comprise: a first cell group index of a first secondary cellgroup and a first time alignment timer value for the first secondarycell group. The base station may, before transmission of said fifthmessage, encrypt the fifth message and protect the fifth message by anintegrity header. The fifth message may further include configurationinformation for physical channels for the wireless device. The fifthmessage may be configured to cause the wireless device to set up ormodify at least one radio bearer. The fifth message may be configured tofurther cause the wireless device to configure at least one of aphysical layer parameter, a MAC layer parameter, and an RLC layerparameter. The plurality of cells of the target base station may be inmore than one frequency band, for example, one or more cells may be infrequency band A and one or more other cells may be in frequency band B(inter-band carrier aggregation). The wireless device may supportconfiguration of a first plurality of cell groups.

According to some of the various aspects of embodiments, a serving eNBmay modify TAG configuration of an SCell by removing (releasing) theSCell and adding a new SCell (with same physical cell ID and frequency)with an updated TAG index. An SCell may be released, for example,employing sCellToReleaseList IE in RRC Connection Reconfigurationmessage and be added employing sCelltoaddmodList IE with a different TAGindex. During a handover process, there may be no need for explicitlyrelease the cells (for example, employing sCellToReleaseList IE) forreconfiguration of TAG configuration. The RRC Connection Reconfigurationmessage with MobilityControlInfo IE (mobility control information) maycomprise an updated TAG configuration, in which cells are assigned totiming advance groups. The updated TAG configuration may, for example,be configured for connection of the UE with a target base station or thesame base station.

FIG. 10 is an example flow diagram in a wireless device illustratingchanging configuration of cell groups as per an aspect of an embodimentof the present invention. According to some of the various aspects ofembodiments, a wireless device may receive, at least one first controlmessage from a base station at block 1000. The at least one firstcontrol message may be configured to cause configuration of a pluralityof cells in the wireless device. The plurality of cells may comprise aprimary cell and at least one secondary cell. A secondary cell in theplurality of cells may be identified by a cell index. The configurationmay assign a secondary cell in the plurality of cells to a cell groupusing the cell group index. The cell group index may identify one of aplurality of cell groups. The plurality of cell groups may comprise aprimary cell group and a secondary cell group. The primary cell groupmay comprise a first subset of the plurality of cells. The first subsetmay comprise the primary cell. The secondary cell group may comprise asecond subset of the at least one secondary cell.

TAG configuration of a wireless device may be reconfigured employing RRCconnection reconfiguration message at block 1002. The wireless devicemay receive an RRC Connection Reconfiguration message. The ConnectionReconfiguration message may or may not include mobility controlinformation (in MobilityControlInfo Information Element). If mobilitycontrol information is included, the wireless device may start ahandover process by performing a handover to a target base station asspecified in the Connection Reconfiguration message. The wireless mayalso start a handover process with a different sector, or may remainconnected to the same sector of the base station as specified in theConnection Reconfiguration message.

Processes for a TAG configuration change employing RRC ConnectionReconfiguration message may be different depending on whether mobilitycontrol information is included in the RRC Connection Reconfigurationmessage. If the RRC Connection Reconfiguration message includes mobilitycontrol information (in MobilityControlInfo Information Element), theRRC Connection Reconfiguration message may re-assign a cell to anupdated cell group without explicitly releasing the cell usingSCellReleaseList IE. The updated cell group is configurable (capable) ofbeing different from a currently configured cell group in the servingbase station. An RRC Connection Reconfiguration message with mobilitycontrol information may reconfigure the TAG index associated with a cellto a different TAG index without explicitly releasing the secondary cellusing sCellToReleaseList IE.

If the RRC Connection Reconfiguration message does not include mobilitycontrol information, the RRC Connection Reconfiguration message may beunconfigurable (incapable) of updating mapping between a given secondarycell and a cell group to a different cell group while the givensecondary cell is configured. In this case, The RRC ConnectionReconfiguration message may be configurable (capable) of updatingmapping between the given secondary cell and a cell group to a differentcell group, if the given secondary cell is released and added with adifferent configured cell group index. The secondary cell may bereleased employing sCellToReleaseList IE and may be added employingsCellToAddModList IE with a different cell group index.

In an example embodiment, TAG ID of a cell may not be simply changedusing sCellToAddModList (without using mobility control informationelement) when the cell is configured. Each TAG may have its own timingreference, when a cell is moved from one TAG to another TAG. It mayrequire changing its timing from one TAG to another TAG quickly andtherefore this may result in timing irregularity in signals. A quickchange in cell timing may be undesirable or difficult to implement. Thisissue which may result in a timing jump in cell timing may createundesirable interference and may increase bit error rate in the cell.There is a need to provide solutions for TAG configuration change indifferent scenarios. Such a solution may reduce unwanted interferenceand bit error rate during TAG change.

According to some of the various aspects of embodiments, a wirelessdevice may receive at least one first control message from a basestation at block 1000. The at least one first control message may beconfigured to cause configuration of a plurality of cells in thewireless device. The plurality of cells may comprise a primary cell andat least one secondary cell. Each of the at least one secondary cell maybe identified by a cell index. The configuration may assign a secondarycell to a cell group identified by a cell group index. The plurality ofcell groups may comprise a primary cell group and a secondary cellgroup. The primary cell group may comprise a first subset of theplurality of cells. The first subset may comprise the primary cell. Thesecondary cell group may comprise a second subset of the at least onesecondary cell. For example, in a TAG configuration, Cell 1 (PHY CellID=1) and Cell 2 (PHY Cell ID=2) may be assigned to sTAG index 1, andCell 3 (PHY Cell ID=3) and Cell 4 (PHY Cell ID=4) may be assigned tosTAG index 2. Cell 5 (PHY Cell ID=5) may be assigned to the primary TAG(TAG index=0). TAG configuration may be configured in the wirelessdevice employing information in the received RRC connectionreconfiguration messages. The base station may require changing TAGconfiguration due to various reasons as described in the specifications.Examples comprise UE mobility, changes in channel conditions, trafficand load, and/or the like.

The wireless device may receive an RRC Connection Reconfigurationmessage. The RRC connection reconfiguration message may be employed tochange TAG configuration in the wireless device at block 1002. If theRRC Connection Reconfiguration message comprises mobility controlinformation, the RRC Connection Reconfiguration message may update cellgroup configuration. This reconfiguration may be performed selectivelyby the base station. The base station may change the TAG configurationor may not change the TAG configuration based on a set of predefinedcriteria. If the RRC connection reconfiguration message comprisesMobility Control information element, then the RRC connectionreconfiguration message is capable of changing TAG configuration withoutexplicitly releasing the cells. An RRC connection reconfigurationmessage with mobility control information may configure cells, forexample, it may configure a new primary cell and a new set of secondarycells. It may also reconfigure TAG configuration depending on channel,traffic and other parameters in the network. After RRC connectionreconfiguration message with mobility control information is received,the wireless device may consider the new configuration and may start arandom access process with the primary cell (as identified in RRCconnection reconfiguration message with mobility control information).There is no need to explicitly release cells, using sCelltoreleaselist,before a TAG associated with a cell is modified. In the example TAGconfiguration provided above, after cell group reconfiguration isapplied, SCell 1, 2, and 3 may be assigned to sTAG index 1, and SCell 4may be assigned to sTAG index 1. This is an example reconfigurationpossibility. sTAG index of an SCell index 3 is modified without theSCell 3 being explicitly released employing sCelltoreleaselist. Inanother example reconfiguration with RRC message includingMobilityControlInfo IE, the cell with (PHY Cell ID=1) may be configuredas primary cell as a part of pTAG. And Cell 1 (PHY Cell ID=1), Cell 2(PHY Cell ID=2), Cell 3 (PHY Cell ID=3), and Cell 4 (PHY Cell ID=4) maybe assigned to sTAG index 1. In this example, a new cell is assigned asthe pCell after RRC message is processed.

According to some of the various aspects of embodiments, if the RRCConnection Reconfiguration message does not comprise mobility controlinformation, a different process may be employed for changing theassociations of an SCell index to an sTAG index. The RRC ConnectionReconfiguration message without Mobility control information element maybe incapable of updating mapping between a first cell and a cell groupto a different cell group while a first cell is configured. The RRCConnection Reconfiguration message may be capable of updating mappingbetween the first cell and the first cell group to a different cellgroup, if the first cell is released and then added again. For example,in a TAG configuration, sTAG index 1 may be associated with SCell 1 and2, and sTAG index 2 may be associated with SCell 3 and 4. pTAG withindex 0 may comprise the primary cell. In order to achieve an updatedconfiguration in which sTAG index 1 may be associated with SCell 1, 2,and 3, and sTAG index 2 may be associated with SCell 4. SCell index 3may be released employing sCelltoreleaselist and may then be added again(with the same or different cell index) using sCellToAddModList with anew TAG ID. SCell release and addition may be performed in the same RRCconnection reconfiguration message or in different RRC configurationmessages.

According to some of the various aspects of embodiments, if the RRCConnection Reconfiguration message comprises mobility controlinformation, the RRC Connection Reconfiguration message may initiate ahandover from the base station to a target base station. If the RRCConnection Reconfiguration message comprises mobility controlinformation, the RRC Connection Reconfiguration message may initiate ahandover from a sector of the base station to a target sector of thebase station (in an example the source sector and the target sector maybe the same sector of the same base station). If the RRC ConnectionReconfiguration message comprises mobility control information, the RRCConnection Reconfiguration message may change the primary cell with afirst physical cell identifier to a different primary cell with adifferent physical cell identifier. In an example embodiment, if the RRCConnection Reconfiguration message comprises mobility controlinformation, the second cell group index may be a cell group configuredfor communication between the wireless device and a target base station.If the RRC Connection Reconfiguration message comprises mobility controlinformation, the RRC Connection Reconfiguration message may initiates ahandover from the base station to a target base station, and the firstcell index may be associated with a cell of the target base stationafter the handover is completed.

FIG. 11 is an example flow diagram in a base station illustratingchanging configuration of cell groups as per an aspect of an embodimentof the present invention. According to some of the various aspects ofembodiments, a base station may transmit at least one first controlmessage to a wireless device at block 1102. The at least one firstcontrol message may be configured to cause configuration of a pluralityof cells in the wireless device. The plurality of cells may comprise afirst cell and at least one second cell, each cell in the plurality ofcells may be identified by a physical cell identifier. The configurationmay assign a cell in the plurality of cells to a cell group identifiedby a cell group index. The cell group index may identify one of aplurality of cell groups. The plurality of cell groups may comprise aprimary cell group and a secondary cell group. A primary cell group maycomprise a first subset of the plurality of cells. The first subset maycomprise the first cell. The secondary cell group may comprise a secondsubset of the at least one second cell. Each cell in the plurality ofcells may comprise a downlink carrier with a given downlink frequency.The physical cell identifier of each cell may be broadcasted employing asynchronization signal transmitted on the cell. The synchronizationsignal may comprise a primary synchronization signal and a secondarysynchronization signal.

The base station may require changing TAG configuration due to variousreasons as described in the specifications. Examples comprise UEmobility, changes in channel conditions, traffic and load, and/or thelike. The base station may transmit an RRC Connection Reconfigurationmessage to a wireless device. The RRC connection reconfiguration messagemay be employed to change TAG configuration in the wireless device atblock 1102. The base station may transmit at least one RRC ConnectionReconfiguration message to modify some of the associations among theplurality of cells and the plurality of cell groups. In order to changea first cell group index associated with the first cell, the at leastone RRC Connection Reconfiguration message: a) may add the first cellwith an updated first cell group index different from the first cellgroup index; and b) may be transmitted with MobilityControlInfoInformation Element. This method may work if the first cell is a primarycell or a secondary cell. In example embodiments, this method isadvantageous from signalling perspective if the first cell is a primarycell. In other words, if the first cell is the primary cell, the atleast one second RRC message may be configured to cause the wirelessdevice to reconfigure the primary cell as a secondary cell with anupdated first cell group index different from the first cell groupindex. And the at least one second RRC message may comprise mobilitycontrol information

In order to change the first cell group index with at least one RRCConnection Reconfiguration message including MobilityControlInfoInformation Element, the at least one RRC Connection Reconfigurationmessage adds the first cell, for example, with the updated first cellgroup index without explicitly releasing the first cell. In an exampleimplementation, the first cell may be a primary cell of the base stationbefore the RRC reconfiguration message is received. The first cell maybe configured as a secondary cell after the RRC reconfiguration messageis received and successfully processed by the wireless device. The atleast one RRC Connection Reconfiguration message withMobilityControlInfo information element may change cell category of thefirst cell from a primary cell to a secondary cell for the wirelessdevice and also change cell group assignments. In an exampleimplementation, the at least one RRC Connection Reconfiguration messagewith MobilityControlInfo information element may change cell category ofone of the cell(s) in the at least one secondary cell from a secondarycell to a new primary cell for the wireless device. The wireless devicemay start random access process with the base station on the new primarycell. Configured cells in the wireless device, except the new primarycell, may be deactivated in the wireless device after the RRCReconfiguration message is received. The base station may send MACactivation command(s) to activate secondary cells. The base station maytransmit PDCCH order to start random access process on a secondary cellof a secondary TAG after it activated the secondary cell.

According to some of the various aspects of embodiments, in order tochange a second cell group index associated with one of the at least onesecondary cell, the at least one RRC Connection Reconfiguration message:may release the one of the at least one second cell; may add the one ofthe at least one second cell with an updated second cell group indexdifferent from the second cell group index; and/or may be transmittedwithout MobilityControlInfo information element. The cell release may beperformed employing SCelltoreleaselist information element in an RRCconnection reconfiguration message. The cell addition may be performedemploying SCelltoaddmodlist information element in an RRC connectionreconfiguration message. In an example embodiment, SCelltoreleaselistand SCelltoaddmodlist information element may be comprised in the sameRRC connection configuration message. In another example,SCelltoreleaselist and SCelltoaddmodlist information element may becomprised in the different RRC connection configuration messages.

According to some of the various aspects of embodiments, the randomaccess procedure may be initiated by a PDCCH order or by the MACsublayer itself. Random access procedure on an SCell may be initiated bya PDCCH order. If a UE receives a PDCCH transmission consistent with aPDCCH order masked with its C-RNTI (radio network temporary identifier),and for a specific serving cell, the UE may initiate a random accessprocedure on this serving cell. For random access on the PCell a PDCCHorder or RRC optionally indicate the ra-PreambleIndex and thera-PRACH-MaskIndex; and for random access on an SCell, the PDCCH orderindicates the ra-PreambleIndex with a value different from zero and thera-PRACH-MaskIndex. For the pTAG preamble transmission on PRACH andreception of a PDCCH order may only be supported for PCell.

According to some of the various aspects of embodiments, the proceduremay use some of the following information: a) the available set of PRACHresources for the transmission of the random access preamble,prach-ConfigIndex, b) for PCell, the groups of random access preamblesand/or the set of available random access preambles in each group, c)for PCell, the preambles that are contained in random access preamblesgroup A and Random Access Preambles group B are calculated, d) the RAresponse window size ra-ResponseWindowSize, e) the power-ramping factorpowerRampingStep, f) the maximum number of preamble transmissionpreambleTransMax, g) the initial preamble powerpreamblelnitialReceivedTargetPower, h) the preamble format based offsetDELTA_PREAMBLE, i) for PCell, the maximum number of Msg3 HARQtransmissions maxHARQ-Msg3Tx, j) for PCell, the Contention ResolutionTimer mac-ContentionResolutionTimer. These parameters may be updatedfrom upper layers before each Random Access procedure is initiated.

According to some of the various aspects of embodiments, the RandomAccess procedure may be performed as follows: Flush the Msg3 buffer; setthe PREAMBLE_TRANSMISSION_COUNTER to 1; set the backoff parameter valuein the UE to 0 ms; for the RN (relay node), suspend any RN subframeconfiguration; proceed to the selection of the Random Access Resource.There may be one Random Access procedure ongoing at any point in time.If the UE receives a request for a new Random Access procedure whileanother is already ongoing, it may be up to UE implementation whether tocontinue with the ongoing procedure or start with the new procedure.

According to some of the various aspects of embodiments, the RandomAccess Resource selection procedure may be performed as follows. Ifra-PreambleIndex (Random Access Preamble) and ra-PRACH-MaskIndex (PRACHMask Index) have been explicitly signalled and ra-PreambleIndex is notzero, then the Random Access Preamble and the PRACH Mask Index may bethose explicitly signalled. Otherwise, the Random Access Preamble may beselected by the UE.

The UE may determine the next available subframe containing PRACHpermitted by the restrictions given by the prach-Configlndex, the PRACHMask Index and physical layer timing requirements (a UE may take intoaccount the possible occurrence of measurement gaps when determining thenext available PRACH subframe). If the transmission mode is TDD and thePRACH Mask Index is equal to zero, then if ra-PreambleIndex wasexplicitly signalled and it was not 0 (i.e., not selected by MAC), thenrandomly select, with equal probability, one PRACH from the PRACHsavailable in the determined subframe. Else, the UE may randomly select,with equal probability, one PRACH from the PRACHs available in thedetermined subframe and the next two consecutive subframes. If thetransmission mode is not TDD or the PRACH Mask Index is not equal tozero, a UE may determine a PRACH within the determined subframe inaccordance with the requirements of the PRACH Mask Index. Then the UEmay proceed to the transmission of the Random Access Preamble.

PRACH mask index values may range for example from 0 to 16. PRACH maskindex value may determine the allowed PRACH resource index that may beused for transmission. For example, PRACH mask index 0 may mean that allPRACH resource indeces are allowed; or PRACH mask index 1 may mean thatPRACH resource index 0 may be used. PRACH mask index may have differentmeaning in TDD and FDD systems.

The random-access procedure may be performed by UE settingPREAMBLE_RECEIVED_TARGET_POWER topreambleInitialReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep.The UE may instruct the physical layer to transmit a preamble using theselected PRACH, corresponding RA-RNTI, preamble index andPREAMBLE_RECEIVED_TARGET_POWER.

According to some of the various aspects of embodiments, once the randomaccess preamble is transmitted and regardless of the possible occurrenceof a measurement gap, the UE may monitor the PDCCH of the PCell forrandom access response(s) identified by the RA-RNTI (random access radionetwork identifier) a specific RA-RNTI defined below, in the randomaccess response (RAR) window which may start at the subframe thatcontains the end of the preamble transmission plus three subframes andhas length ra-ResponseWindowSize subframes. The specific RA-RNTIassociated with the PRACH in which the Random Access Preamble istransmitted, is computed as: RA-RNTI=1+t_id+10*f_id. Where t_id may bethe index of the first subframe of the specified PRACH (0≦t_id<10), andf_id is the index of the specified PRACH within that subframe, inascending order of frequency domain (0≦f_id<6). The UE may stopmonitoring for RAR(s) after successful reception of a RAR containingrandom access preamble identifiers that matches the transmitted randomaccess preamble.

According to some of the various aspects of embodiments, if a downlinkassignment for this TTI (transmission tme interval) has been received onthe PDCCH for the RA-RNTI and the received TB (transport block) issuccessfully decoded, the UE may regardless of the possible occurrenceof a measurement gap: if the RAR contains a backoff indicator (BI)subheader, set the backoff parameter value in the UE employing the BIfield of the backoff indicator subheader, else, set the backoffparameter value in the UE to zero ms. If the RAR contains a randomaccess preamble identifier corresponding to the transmitted randomaccess preamble, the UE may consider this RAR reception successful andapply the following actions for the serving cell where the random accesspreamble was transmitted: process the received riming advance commandfor the cell group in which the preamble was transmitted, indicate thepreamblelnitialReceivedTargetPower and the amount of power rampingapplied to the latest preamble transmission to lower layers (i.e.,(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep); process thereceived uplink grant value and indicate it to the lower layers; theuplink grant is applicable to uplink of the cell in which the preamblewas transmitted. If ra-Preamblelndex was explicitly signalled and it wasnot zero (e.g., not selected by MAC), consider the random accessprocedure successfully completed. Otherwise, if the Random AccessPreamble was selected by UE MAC, set the Temporary C-RNTI to the valuereceived in the RAR message. When an uplink transmission is required,e.g., for contention resolution, the eNB may not provide a grant smallerthan 56 bits in the Random Access Response.

According to some of the various aspects of embodiments, if no RAR isreceived within the RAR window, or if none of all received RAR containsa random access preamble identifier corresponding to the transmittedrandom access preamble, the random access response reception mayconsidered not successful. If RAR is not received, UE may incrementPREAMBLE_TRANSMISSION_COUNTER by 1. IfPREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1 and random accesspreamble is transmitted on the PCell, then UE may indicate a randomaccess problem to upper layers (RRC). This may result in radio linkfailure. If PREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1 and therandom access preamble is transmitted on an SCell, then UE may considerthe random access procedure unsuccessfully completed. UE may stay in RRCconnected mode and keep the RRC connection active eventhough a randomaccess procedure unsuccessfully completed on a secondary TAG. Accordingto some of the various aspects of embodiments, at completion of therandom access procedure, the UE may discard explicitly signalledra-Preamblelndex and ra-PRACH-Masklndex, if any; and flush the HARQbuffer used for transmission of the MAC PDU in the Msg3 buffer. Inaddition, the RN may resume the suspended RN subframe configuration, ifany.

According to some of the various aspects of embodiments, a UE may have aconfigurable timer timeAlignmentTimer per TAG. The timeAlignmentTimer isused to control how long the UE considers the Serving Cells belonging tothe associated TAG to be uplink time aligned (in-sync). When a TimingAdvance Command MAC control element is received, the UE may apply theriming advance command for the indicated TAG, and start or restart thetimeAlignmentTimer associated with the indicated TAG. When a timingadvance command is received in a RAR message for a serving cellbelonging to a TAG andif the random access preamble was not selected byUE MAC, the UE may apply the timing advance command for this TAG, andmay start or restart the timeAlignmentTimer associated with this TAG.When a timeAlignmentTimer associated with the pTAG expires, the UE may:flush all HARQ buffers for all serving cells; notify RRC to releasePUCCH/SRS for all serving cells; clear any configured downlinkassignments and uplink grants; and consider all runningtimeAlignmentTimers as expired. When a timeAlignmentTimer associatedwith an sTAG expires, then for all Serving Cells belonging to this TAG,the UE may flush all HARQ buffers; and notify RRC to release SRS. The UEmay not perform any uplink transmission on a serving Cell except therandom access preamble transmission when the timeAlignmentTimerassociated with the TAG to which this serving cell belongs is notrunning. When the timeAlignmentTimer associated with the pTAG is notrunning, the UE may not perform any uplink transmission on any servingcell except the random access preamble transmission on the PCell. A UEstores or maintains N_TA (current timing advance value of an sTAG) uponexpiry of associated timeAlignmentTimer. The UE may apply a receivedtiming advance command MAC control element and starts associatedtimeAlignmentTimer. Transmission of the uplink radio frame number i fromthe UE may start (N_(TA)+N_(TA offset))×T_(s) seconds before the startof the corresponding downlink radio frame at the UE, where0≦N_(TA)≦20512. In an example implementation, N_(TA offset)=0 for framestructure type 1 (FDD) and N_(TA offset)=624 for frame structure type 2(TDD).

According to some of the various aspects of embodiments, upon receptionof a timing advance command for a TAG containing the primary cell, theUE may adjust uplink transmission timing for PUCCH/PUSCH/SRS of theprimary cell based on the received timing advance command. The ULtransmission timing for PUSCH/SRS of a secondary cell may be the same asthe primary cell if the secondary cell and the primary cell belong tothe same TAG. Upon reception of a timing advance command for a TAG notcontaining the primary cell, the UE may adjust uplink transmissiontiming for PUSCH/SRS of secondary cells in the TAG based on the receivedtiming advance command where the UL transmission timing for PUSCH/SRS isthe same for all the secondary cells in the TAG.

The timing advance command for a TAG may indicates the change of theuplink timing relative to the current uplink timing for the TAG asmultiples of 16Ts (Ts: sampling time unit). The start timing of therandom access preamble may obtained employing a downlink synchronizationtime in the same TAG. In case of random access response, an 11-bittiming advance command, TA, for a TAG may indicate NTA values by indexvalues of TA=0, 1, 2, . . . , 1282, where an amount of the timealignment for the TAG may be given by NTA=TA×16. In other cases, a 6-bittiming advance command, TA, for a TAG may indicate adjustment of thecurrent NTA value, NTA, old, to the new NTA value, NTA, new, by indexvalues of TA=0, 1, 2, . . . , 63, where NTA, new=NTA, old+(TA−31)×16.Here, adjustment of NTA value by a positive or a negative amountindicates advancing or delaying the uplink transmission timing for theTAG by a given amount respectively. For a timing advance commandreceived on subframe n, the corresponding adjustment of the uplinktransmission timing may apply from the beginning of subframe n+6. Forserving cells in the same TAG, when the UE's uplink PUCCH/PUSCH/SRStransmissions in subframe n and subframe n+1 are overlapped due to thetiming adjustment, the UE may complete transmission of subframe n andnot transmit the overlapped part of subframe n+1. If the receiveddownlink timing changes and is not compensated or is only partlycompensated by the uplink timing adjustment without timing advancecommand, the UE may change NTA accordingly.

Downlink frames and subframes of downlink carriers may be time aligned(by the base station) in carrier aggregation and multiple TAGconfiguration. Time alignment errors may be tolerated to some extend.For example, for intra-band contiguous carrier aggregation, timealignment error may not exceed 130 ns. In another example, forintra-band non-contiguous carrier aggregation, time alignment error maynot exceed 260 ns. In another example, for inter-band carrieraggregation, time alignment error may not exceed 1.3 μs.

The UE may have capability to follow the frame timing change of theconnected base station. The uplink frame transmission may take place(N_(TA)+N_(TA offset))×T_(s) before the reception of the first detectedpath (in time) of the corresponding downlink frame from the referencecell. The UE may be configured with a pTAG containing the PCell. ThepTAG may also contain one or more SCells, if configured. The UE may alsobe configured with one or more sTAGs, in which case the pTAG may containone PCell and the sTAG may contain at least one SCell with configureduplink. In pTAG, UE may use the PCell as the reference cell for derivingthe UE transmit timing for cells in the pTAG. The UE may employ asynchronization signal on the reference cell to drive downlink timing.When a UE is configured with an sTAG, the UE may use an activated SCellfrom the sTAG for deriving the UE transmit timing for cell in the sTAG.

In at least one of the various embodiments, uplink physical channel(s)may correspond to a set of resource elements carrying informationoriginating from higher layers. The following example uplink physicalchannel(s) may be defined for uplink: a) Physical Uplink Shared Channel(PUSCH), b) Physical Uplink Control Channel (PUCCH), c) Physical RandomAccess Channel (PRACH), and/or the like. Uplink physical signal(s) maybe used by the physical layer and may not carry information originatingfrom higher layers. For example, reference signal(s) may be consideredas uplink physical signal(s). Transmitted signal(s) in slot(s) may bedescribed by one or several resource grids including, for example,subcarriers and SC-FDMA or OFDMA symbols. Antenna port(s) may be definedsuch that the channel over which symbol(s) on antenna port(s) may beconveyed and/or inferred from the channel over which other symbol(s) onthe same antenna port(s) is/are conveyed. There may be one resource gridper antenna port. The antenna port(s) used for transmission of physicalchannel(s) or signal(s) may depend on the number of antenna port(s)configured for the physical channel(s) or signal(s).

According to some of the various embodiments, physical downlink controlchannel(s) may carry transport format, scheduling assignments, uplinkpower control, and other control information. PDCCH may support multipleformats. Multiple PDCCH packets may be transmitted in a subframe.According to some of the various embodiments, scheduling controlpacket(s) may be transmitted for packet(s) or group(s) of packetstransmitted in downlink shared channel(s). Scheduling control packet(s)may include information about subcarriers used for packettransmission(s). PDCCH may also provide power control commands foruplink channels. PDCCH channel(s) may carry a plurality of downlinkcontrol packets in subframe(s). Enhance PDCCH may be implemented in acell as an option to carrier control information. According to some ofthe various embodiments, PHICH may carry the hybrid-ARQ (automaticrepeat request) ACK/NACK.

Other arrangements for PCFICH, PHICH, PDCCH, enhanced PDCCH, and/orPDSCH may be supported. The configurations presented here are forexample purposes. In another example, resources PCFICH, PHICH, and/orPDCCH radio resources may be transmitted in radio resources including asubset of subcarriers and pre-defined time duration in each or some ofthe subframes. In an example, PUSCH resource(s) may start from the firstsymbol. In another example embodiment, radio resource configuration(s)for PUSCH, PUCCH, and/or PRACH (physical random access channel) may usea different configuration. For example, channels may be timemultiplexed, or time/frequency multiplexed when mapped to uplink radioresources.

According to some of the various aspects of embodiments, the physicallayer random access preamble may comprise a cyclic prefix of length Tcpand a sequence part of length Tseq. The parameter values may bepre-defined and depend on the frame structure and a random accessconfiguration. In an example embodiment, Tcp may be 0.1 msec, and Tseqmay be 0.9 msec. Higher layers may control the preamble format. Thetransmission of a random access preamble, if triggered by the MAC layer,may be restricted to certain time and frequency resources. The start ofa random access preamble may be aligned with the start of thecorresponding uplink subframe at a wireless device with N_TA=0.

According to an example embodiment, random access preambles may begenerated from Zadoff-Chu sequences with a zero correlation zone,generated from one or several root Zadoff-Chu sequences. In anotherexample embodiment, the preambles may also be generated using otherrandom sequences such as Gold sequences. The network may configure theset of preamble sequences a wireless device may be allowed to use.According to some of the various aspects of embodiments, there may be amultitude of preambles (e.g. 64) available in cell(s). From the physicallayer perspective, the physical layer random access procedure mayinclude the transmission of random access preamble(s) and random accessresponse(s). Remaining message(s) may be scheduled for transmission by ahigher layer on the shared data channel and may not be considered partof the physical layer random access procedure. For example, a randomaccess channel may occupy 6 resource blocks in a subframe or set ofconsecutive subframes reserved for random access preamble transmissions.

According to some of the various embodiments, the following actions maybe followed for a physical random access procedure: 1) layer 1 proceduremay be triggered upon request of a preamble transmission by higherlayers; 2) a preamble index, a target preamble received power, acorresponding RA-RNTI (random access-radio network temporary identifier)and/or a PRACH resource may be indicated by higher layers as part of arequest; 3) a preamble transmission power P_PRACH may be determined; 4)a preamble sequence may be selected from the preamble sequence set usingthe preamble index; 5) a single preamble may be transmitted usingselected preamble sequence(s) with transmission power P_PRACH on theindicated PRACH resource; 6) detection of a PDCCH with the indicated RARmay be attempted during a window controlled by higher layers; and/or thelike. If detected, the corresponding downlink shared channel transportblock may be passed to higher layers. The higher layers may parsetransport block(s) and/or indicate an uplink grant to the physicallayer(s).

Before a wireless device initiates transmission of a random accesspreamble, it may access one or many of the following types ofinformation: a) available set(s) of PRACH resources for the transmissionof a random access preamble; b) group(s) of random access preambles andset(s) of available random access preambles in group(s); c) randomaccess response window size(s); d) power-ramping factor(s); e) maximumnumber(s) of preamble transmission(s); f) initial preamble power; g)preamble format based offset(s); h) contention resolution timer(s);and/or the like. These parameters may be updated from upper layers ormay be received from the base station before random access procedure(s)may be initiated.

According to some of the various aspects of embodiments, a wirelessdevice may select a random access preamble using available information.The preamble may be signaled by a base station or the preamble may berandomly selected by the wireless device. The wireless device maydetermine the next available subframe containing PRACH permitted byrestrictions given by the base station and the physical layer timingrequirements for TDD or FDD. Subframe timing and the timing oftransmitting the random access preamble may be determined based, atleast in part, on synchronization signals received from the base stationand/or the information received from the base station. The wirelessdevice may proceed to the transmission of the random access preamblewhen it has determined the timing. The random access preamble may betransmitted on a second plurality of subcarriers on the first uplinkcarrier.

According to some of the various aspects of embodiments, once a randomaccess preamble is transmitted, a wireless device may monitor the PDCCHof a primary carrier for random access response(s), in a random accessresponse window. There may be a pre-known identifier in PDCCH thatidentifies a random access response. The wireless device may stopmonitoring for random access response(s) after successful reception of arandom access response containing random access preamble identifiersthat matches the transmitted random access preamble and/or a randomaccess response address to a wireless device identifier. A base stationrandom access response may include a time alignment command. Thewireless device may process the received time alignment command and mayadjust its uplink transmission timing according the time alignment valuein the command. For example, in a random access response, a timealignment command may be coded using 11 bits, where an amount of thetime alignment may be based on the value in the command. In an exampleembodiment, when an uplink transmission is required, the base stationmay provide the wireless device a grant for uplink transmission.

If no random access response is received within the random accessresponse window, and/or if none of the received random access responsescontains a random access preamble identifier corresponding to thetransmitted random access preamble, the random access response receptionmay be considered unsuccessful and the wireless device may, based on thebackoff parameter in the wireless device, select a random backoff timeand delay the subsequent random access transmission by the backoff time,and may retransmit another random access preamble.

According to some of the various aspects of embodiments, a wirelessdevice may transmit packets on an uplink carrier. Uplink packettransmission timing may be calculated in the wireless device using thetiming of synchronization signal(s) received in a downlink. Uponreception of a timing alignment command by the wireless device, thewireless device may adjust its uplink transmission timing. The timingalignment command may indicate the change of the uplink timing relativeto the current uplink timing. The uplink transmission timing for anuplink carrier may be determined using time alignment commands and/ordownlink reference signals.

According to some of the various aspects of embodiments, a timealignment command may indicate timing adjustment for transmission ofsignals on uplink carriers. For example, a time alignment command mayuse 6 bits. Adjustment of the uplink timing by a positive or a negativeamount indicates advancing or delaying the uplink transmission timing bya given amount respectively.

For a timing alignment command received on subframe n, the correspondingadjustment of the timing may be applied with some delay, for example, itmay be applied from the beginning of subframe n+6. When the wirelessdevice's uplink transmissions in subframe n and subframe n+1 areoverlapped due to the timing adjustment, the wireless device maytransmit complete subframe n and may not transmit the overlapped part ofsubframe n+1.

According to some of the various aspects of embodiments, a wirelessdevice may be preconfigured with one or more carriers. When the wirelessdevice is configured with more than one carrier, the base station and/orwireless device may activate and/or deactivate the configured carriers.One of the carriers (the primary carrier) may always be activated. Othercarriers may be deactivated by default and/or may be activated by a basestation when needed. A base station may activate and deactivate carriersby sending an activation/deactivation MAC control element. Furthermore,the UE may maintain a carrier deactivation timer per configured carrierand deactivate the associated carrier upon its expiry. The same initialtimer value may apply to instance(s) of the carrier deactivation timer.The initial value of the timer may be configured by a network. Theconfigured carriers (unless the primary carrier) may be initiallydeactivated upon addition and after a handover.

According to some of the various aspects of embodiments, if a wirelessdevice receives an activation/deactivation MAC control elementactivating the carrier, the wireless device may activate the carrier,and/or may apply normal carrier operation including: sounding referencesignal transmissions on the carrier (if the carrier is uplink timealigned), CQI (channel quality indicator)/PMI(precoding matrixindicator)/RI(ranking indicator) reporting for the carrier, PDCCHmonitoring on the carrier, PDCCH monitoring for the carrier, start orrestart the carrier deactivation timer associated with the carrier,and/or the like. If the device receives an activation/deactivation MACcontrol element deactivating the carrier, and/or if the carrierdeactivation timer associated with the activated carrier expires, thebase station or device may deactivate the carrier, and may stop thecarrier deactivation timer associated with the carrier, and/or may flushHARQ buffers associated with the carrier.

If PDCCH on a carrier scheduling the activated carrier indicates anuplink grant or a downlink assignment for the activated carrier, thedevice may restart the carrier deactivation timer associated with thecarrier. When a carrier is deactivated, the wireless device may nottransmit SRS (sounding reference signal) for the carrier, may not reportCQI/PMI/RI for the carrier, may not transmit on UL-SCH for the carrier,may not monitor the PDCCH on the carrier, and/or may not monitor thePDCCH for the carrier.

In this specification, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” In this specification,the term “may” is to be interpreted as “may, for example,” In otherwords, the term “may” is indicative that the phrase following the term“may” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.If A and B are sets and every element of A is also an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}.

In this specification, parameters (Information elements: IEs) maycomprise one or more objects, and each of those objects may comprise oneor more other objects. For example, if parameter (IE) N comprisesparameter (IE) M, and parameter (IE) M comprises parameter (IE) K, andparameter (IE) K comprises parameter (information element) J, then, forexample, N comprises K, and N comprises J.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an isolatableelement that performs a defined function and has a defined interface toother elements. The modules described in this disclosure may beimplemented in hardware, software in combination with hardware,firmware, wetware (i.e hardware with a biological element) or acombination thereof, all of which are behaviorally equivalent. Forexample, modules may be implemented as a software routine written in acomputer language configured to be executed by a hardware machine (suchas C, C++, Fortran, Java, Basic, Matlab or the like) or amodeling/simulation program such as Simulink, Stateflow, GNU Octave, orLab VIEWMathScript. Additionally, it may be possible to implementmodules using physical hardware that incorporates discrete orprogrammable analog, digital and/or quantum hardware. Examples ofprogrammable hardware comprise: computers, microcontrollers,microprocessors, application-specific integrated circuits (ASICs); fieldprogrammable gate arrays (FPGAs); and complex programmable logic devices(CPLDs). Computers, microcontrollers and microprocessors are programmedusing languages such as assembly, C, C++ or the like. FPGAs, ASICs andCPLDs are often programmed using hardware description languages (HDL)such as VHSIC hardware description language (VHDL) or Verilog thatconfigure connections between internal hardware modules with lesserfunctionality on a programmable device. Finally, it needs to beemphasized that the above mentioned technologies are often used incombination to achieve the result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the spirit and scope. In fact, after reading theabove description, it will be apparent to one skilled in the relevantart(s) how to implement alternative embodiments. Thus, the presentembodiments should not be limited by any of the above describedexemplary embodiments. In particular, it should be noted that, forexample purposes, the above explanation has focused on the example(s)using FDD communication systems. However, one skilled in the art willrecognize that embodiments of the invention may also be implemented inTDD communication systems. The disclosed methods and systems may beimplemented in wireless or wireline systems. The features of variousembodiments presented in this invention may be combined. One or manyfeatures (method or system) of one embodiment may be implemented inother embodiments. Only a limited number of example combinations areshown to indicate to one skilled in the art the possibility of featuresthat may be combined in various embodiments to create enhancedtransmission and reception systems and methods.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112, paragraph 6. Claims that do not expressly include the phrase“means for” or “step for” are not to be interpreted under 35 U.S.C. 112,paragraph 6.

What is claimed is:
 1. A method comprising: a) transmitting, by aserving base station to a target base station, at least one firstmessage in response to making a handover decision by said serving basestation for a wireless device; b) receiving, by said serving basestation from said target base station, at least one second messagecomprising a plurality of parameters of a plurality of cells for saidwireless device, said plurality of parameters comprising: i)configuration parameters of a primary cell and at least one secondarycell; and ii) a cell group index for a secondary cell in said at leastone secondary cell, said cell group index identifying one of a pluralityof cell groups, said plurality of cell groups comprising: (1) a primarycell group comprising a first subset of said plurality of cells, saidfirst subset comprising said primary cell; and (2) a secondary cellgroup comprising a second subset of said at least one secondary cell;and c) transmitting, by said serving base station to said wirelessdevice, a third message: i) comprising said plurality of parameters; andii) configured to cause said wireless device to start a synchronizationprocess with said target base station.
 2. The method of claim 1, whereinsaid at least one first message comprises at least one parameterindicating whether said wireless device supports configuration of afirst plurality of cell groups.
 3. The method of claim 2, wherein saidat least one parameter further indicates whether said wireless devicesupports configuration of said plurality of cell groups for each of oneor more band combinations supported by said wireless device.
 4. Themethod of claim 1, wherein said third message is configured to furthercause in said wireless device configuration of a time alignment timerfor each of said plurality of cell groups.
 5. The method of claim 1,wherein said third message comprises a media access control dedicatedinformation element comprising a sequence of at least one firstinformation element, each of said at least one first information elementcomprising: a first cell group index of a first secondary cell group anda first time alignment timer value for said first secondary cell group.6. The method of claim 1, further comprising: a) encrypting said thirdmessage; and b) protecting said third message by an integrity header. 7.The method of claim 1, wherein said third message: a) further comprisesconfiguration information for physical channels for said wirelessdevice; and b) is configured to cause said wireless device to set up ormodify at least one radio bearer.
 8. The method of claim 1, wherein saidthird message is configured to further cause said wireless device toconfigure at least one of: a physical layer parameter; a MAC layerparameter; and an RLC layer parameter.
 9. The method of claim 1, whereinsaid plurality of cells of said target base station are in more than onefrequency band.
 10. The method of claim 1, wherein said wireless devicesupports configuration of a first plurality of cell groups.
 11. A methodcomprising: a) transmitting, by a serving base station to a target basestation, at least one first message in response to making a handoverdecision by said serving base station for a wireless device, said atleast one first message comprising at least one parameter indicatingwhether said wireless device supports configuration of a plurality ofcell groups; b) receiving, by said serving base station from said targetbase station, at least one second message comprising a plurality ofparameters of a plurality of cells for said wireless device, saidplurality of parameters comprising: i) configuration parameters of aprimary cell and at least one secondary cell; and ii) a cell group indexfor a secondary cell in said at least one secondary cell, said cellgroup index identifying one of a first plurality of cell groups, saidfirst plurality of cell groups comprising: (1) a primary cell groupcomprising a first subset of said plurality of cells, said first subsetcomprising said primary cell; and (2) a secondary cell group comprisinga second subset of said at least one secondary cell; and c)transmitting, by said serving base station to said wireless device, athird message: i) comprising said plurality of parameters; and ii)configured to cause said wireless device to start a synchronizationprocess with said target base station.
 12. The method of claim 11,wherein said at least one parameter further indicates whether saidwireless device supports configuration of said plurality of cell groupsfor each of one or more band combinations supported by said wirelessdevice.
 13. The method of claim 11, wherein said third messageconfigured to further cause in said wireless device configuration of atime alignment timer for each of said first plurality of cell groups.14. The method of claim 11, wherein said third message comprises a mediaaccess control dedicated information element comprising a sequence of atleast one first information element, each of said at least one firstinformation element comprising: a first cell group index of a firstsecondary cell group and a first time alignment timer value for saidfirst secondary cell group.
 15. The method of claim 11, furthercomprising: a) encrypting said third message; and b) protecting saidthird message by an integrity header.
 16. A serving base stationcomprising: a) one or more communication interfaces; b) one or moreprocessors; and c) memory storing instructions that, when executed,cause said serving base station to: i) transmit at least one firstmessage to a target base station in response to making a handoverdecision by said serving base station for a wireless device; ii)receive, at least one second message from said target base station, saidat least one second message comprising a plurality of parameters of aplurality of cells for said wireless device, said plurality ofparameters comprising: (1) configuration parameters of a primary celland at least one secondary cell; and (2) a cell group index for asecondary cell in said at least one secondary cell, said cell groupindex identifying one of a plurality of cell groups, said plurality ofcell groups comprising: (a) a primary cell group comprising a firstsubset of said plurality of cells, said first subset comprising saidprimary cell; and (b) a secondary cell group comprising a second subsetof said at least one secondary cell; and iii) transmit to said wirelessdevice, a third message: (1) comprising said plurality of parameters;and (2) configured to cause said wireless device to start asynchronization process with said target base station.
 17. The servingbase station of claim 16, wherein said third message: c) furthercomprises configuration information for physical channels for saidwireless device; and d) is configured to cause said wireless device toset up or modify at least one radio bearer.
 18. The serving base stationof claim 16, wherein said third message is configured to cause saidwireless device to configure at least one of: a physical layerparameter; a MAC layer parameter; and an RLC layer parameter.
 19. Theserving base station of claim 16, wherein said plurality of cells ofsaid target base station are in more than one frequency band.
 20. Theserving base station of claim 16, wherein said wireless device supportsconfiguration of a first plurality of cell groups.